The present invention is directed to toothpaste compositions containing cetylpyridinium chloride as an active antibacterial agent which may be used to inhibit the formation of plaque. The composition contains the active agent and at least one surfactant in which the components of the composition do not substantially interfere with the cetylpyridinium chloride and thereby enable the active agent to effectively bind to the teeth to perform its antibacterial function.
Cetylpyridinium chloride is well known as an antibacterial agent especially for the inhibition of plaque formation. This antibacterial agent has been used in commercial liquid mouthwash products such as Scope(copyright) and Cepacol(copyright). The environment of the commercial mouthwash products enables cetylpyridinium chloride to freely contact those oral surfaces which may harbor unwanted microorganisms. However, cetylpyridinium chloride is not effectively employed in many systems because of its tendency to complex with components which carry a negative charge. When bound in this manner, the cetylpyridinium chloride is unavailable for effective contact with tooth surfaces and thereby renders the active agent ineffective for its intended purpose.
Toothpaste compositions typically include an anionic surfactant and often include an artificial sweetener. These components are capable of binding with cetylpyridinium chloride to thereby render the antibacterial agent ineffective. Other components typically found in a toothpaste composition such as an abrasive material are also typically capable of binding to cetylpyridinium chloride.
It would be an advance in the art if toothpaste compositions contained components which did not render cetylpyridinium chloride ineffective but still provide the toothpaste composition with those characteristics which make the toothpaste composition effective as part of oral hygiene care.
The present invention is generally directed to a toothpaste composition in which cetylpyridinium chloride is present as an antibacterial agent as part of an effective oral hygiene program. In a particular aspect of the present invention, there is provided a toothpaste composition comprising:
a) an antibacterial effective amount of cetylpyridinium chloride; and
b) a mixture of toothpaste forming components, including at least one surfactant and optionally at least one sweetener, the sweetener and/or surfactant alone or in combination permitting the cetylpyridinium chloride to effectively bind to the teeth to perform an antibacterial function.
The toothpaste composition of the present invention includes an antibacterial effective amount of cetylpyridinium chloride and other toothpaste components which do not materially prevent the cetylpyridinium chloride from binding to tooth surfaces to perform an antibacterial function. The phrase xe2x80x9cdo not materially preventxe2x80x9d as used herein means that a sufficient amount of cetylpyridinium chloride is available to bind to tooth surfaces to perform an antibacterial function.
Toothpaste compositions contain a number of components which are either active in performing a particular function related to the oral care system afforded by the toothpaste or to a passive function which is employed to provide a composition to enable the active components to perform their function. Examples of active components are tooth whiteners, antibacterial agents, abrasives or polishing materials and the like. Examples of passive components include organic surfactants which assist thorough and complete dispersion of one or more active agents, sweeteners, is preservatives and the like. The organic surfactants may and usually do provide both active cleaning activities as well as passive functions.
The toothpaste compositions of the present invention may vary widely as to the components, but the toothpaste forming components which typically include at least one surfactant and optionally at least one sweetener do not materially prevent cetylpyridinium chloride from binding to tooth surfaces.
Cetylpyridinium chloride is cationic in nature and therefore is attracted to negative surfaces. Tooth surfaces typically have a negative charge and therefore there is a natural attraction of cetylpyridinium chloride for tooth surfaces. However, many conventional toothpaste forming components are anionic and therefore possess a negative charge causing such components to bind to cetylpyridinium chloride and therefore make it unavailable for binding to tooth surfaces.
In accordance with one aspect of the present invention, it has been discovered that the employment of certain amphoteric surfactants eliminates a major portion of the interference of the other components with cetylpyridinium chloride activity. By employing such surfactants, the surfactant performs its natural function without interfering with the cetylpyridinium chloride (the cetylpyridinium chloride and its antibacterial properties are thereby not effectively removed from the toothpaste composition).
In a second aspect of the invention, certain sweeteners have been found to actually disrupt cetylpyridinium chloride activity in the presence of surfactants as compared to the same situation in the absence of such particular sweeteners.
One class of preferred surfactants for use in the present invention are those encompassed by Formula I 
where R1 and R2 are independently an alkyl group of 1-4 carbon atoms, preferably they are the same, and most preferably they are each methyl;
n is an integer of from 1-4;
R3 is a group Ra or (Raxe2x80x94C(O)NH2)xe2x80x94(CH2)m in which m is an integer of from 1-4, and
Ra is an alkyl of 8-20 carbons. Ra is most preferably coco (i.e., a mixture C14 to C16) and m is preferably 3.
The preferred surfactants of those encompassed by Formula I include coco betaine and cocamidopropyl betaine and combinations thereof.
Another class of surfactants which are particularly suitable for use in the present invention are amine oxides encompassed by Formula II 
wherein R4 and R5 which may be the same or different are each independently selected from an alkyl group having 1 to 4 carbon atoms, and R6 is an alkyl group having from 8 to 12 carbon atoms, which is unsubstituted or substituted by at least one C1-C4 alkyl group.
Some specific examples of amine oxides for use in the present invention include dodecyl-methylamine oxide, cocamidopropyl dimethylamine oxide, ether amine oxides and the like. The preferred compounds are N,N-dimethyldodecylamine oxide, N,N-dimethyideclyamine oxide, and N,N-dimethyloctylamine oxide, respectively.
The present toothpaste composition may optionally contain a sweetener which does not materially prevent the cetylpyridinium chloride from binding to tooth surfaces. Desirable sweeteners are those which are not negatively charged and includes those which are cationic, non-ionic or amphoteric in nature. A preferred sweetener is Sucralose manufactured by McNeil Labs of New Brunswick, N.J.
Other components which may be incorporated into the toothpaste composition of the present invention include whiteners, flavorants, humectants, desensitizing agents, thickening agents, abrasives, fluoride providing compounds and the like. Suitable non-ionic thickening agents include (C2-6) alkylene oxide modified (C1-6) alkylcellulose ethers such as hydroxy-ethylcellulose, hydroxy-propylcellulose, hydroxy-propylmethylcellulose and mixtures thereof. Suitable cationic thickening agents include quaternary cellulose derivatives, guar gum derivatives and the like.
Abrasive materials include certain phosphates such as sodium metaphosphate, potassium metaphosphate, tricalcium phosphate, dicalcium phosphate dihydrate, anyhydrous dicalcium phosphate, calcium pyrophosphate, zinc orthophosphate, alumina, hydrated alumina, aluminum silicate, bentonite, calcium carbonate, sodium bicarbonate and the like.
Fluoride-providing compounds include inorganic fluoride salts, such as soluble alkali metal, alkaline earthmetal and heavy metal salts, for example, sodium fluoride, potassium fluoride, ammonium fluoride, lead fluoride, copper fluoride, zinc fluoride, tin fluoride, barium fluoride, sodium fluorosilicate, ammonium fluorosilicate, sodium fluorozirconate, sodium monofluorophosphate, aluminum mono-endifluorophosphate and the like.
Humectants include glycerin, sorbitol, polyethylene glycol, and the like.
Desensitizing agents include potassium salts, and strontium salts especially potassium nitrate, strontium chloride and the like.
In accordance with a preferred aspect of the present invention a cetylpyridinium chloride-containing toothpaste composition containing decylamine oxide alone or in combination with a sweetener, especially sucralose provides significant availability of the antibacterial agent to bind to tooth surfaces. The surfactant cocamidopropyl betaine in combination with Sucralese provides another highly effective toothpaste composition.